Viruses, either those occurring in nature, or recombinant versions thereof, are used for vaccination and in the field of gene therapy. It is possible for many viruses or virus-like particles to safely and efficiently propagate these in cells (see for instance WO 01/38362, which describes the propagation of various viruses in E1-immortalized retina cells). Recombinant adenoviruses are a preferred class of viral vectors for use in gene therapy and for vaccination purposes. Such recombinant adenoviruses are usually deficient in at least the E1 region, and are propagated in complementing cells providing the E1-region, such as 293 cells, or E1-immortalized retina cells such as PER.C6® cells (see for instance U.S. Pat. No. 5,994,128).
After propagation of the viruses in the cells, for virtually all applications it is necessary to purify the viruses from the cells, before further use.
International patent application WO 98/22588 describes methods for the production and purification of adenoviral vectors. The methods comprise growing cells, infecting the cells with adenovirus, harvesting and lysing the cells, concentrating the crude lysate, exchanging the buffer of the crude lysate, treating the lysate with nuclease, and further purifying the virus using chromatography.
Several other publications describe the purification of viruses from cells, mostly discussing the use of specific chromatographic matrices for purification of the virus from a cell lysate, see e.g. U.S. Pat. Nos. 6,008,036, 6,586,226, 5,837,520, 6,261,823, 6,537,793, and international patent applications WO 00/50573, WO 02/44348 and WO 03/078592.
In several industrial processes for purification of viruses, particularly adenoviruses, a step of ultrafiltration is used, mainly to concentrate the virus and/or to exchange the buffer in which the virus is kept.
Despite the description of several processes mainly regarding different chromatography matrices, a need remains for alternative and preferably improved methods for virus purification. The present invention provides such methods.